Comparison study of rotor structures for five-phase synchronous reluctance machines

Five-phase synchronous reluctance machines (SynRM) have a higher torque density over conventional three-phase synchronous reluctance machines due to utilizing the third harmonics in the magnetic field interacting with appropriate armature current. However, for effective utilization of the third harmonics, it is critical that the rotor of the SynRM creates sufficient coupling between the fundamental and third harmonic components in the field. This paper presents a comparison study of the rotor structures for the non-sine five-phase SynRMs with a detailed examination of two different reluctance rotor structures. The comparison results show that with a simple structure, the salient-pole rotor creates strong mutual coupling between the fundamental and third harmonic MMFs and thus outperforms the complicated axially laminated rotor structures for non-sine five-phase SynRMs in terms of torque and ease of manufacturing